| AVS 58th Annual International Symposium and Exhibition | |
| Advanced Surface Engineering Division | Thursday Sessions |
| Session SE+PS-ThA |
| Session: | Pulsed Plasmas in Surface Engineering |
| Presenter: | Rachel Jakubiak, Air Force Research Laboratory |
| Authors: | R. Jakubiak, Air Force Research Laboratory L. Sun, General Dynamics Information Technology N. Murphy, Air Force Research Laboratory A. Waite, Universal Technology Corporation J. Jones, Air Force Research Laboratory |
| Correspondent: | Click to Email |
Multilayer metal -dielectric stacks containing noble metals such as gold, silver, and copper have myriad applications in the areas of linear and nonlinear optics and photonics. The optical dispersion of Ag makes it particularly attractive for optical interference filters and metamaterials applications. In this regard, it is essential for the Ag layers be sufficiently thin as to not inhibit transparency in the visible spectral region yet still exhibit the favorable optical dispersion of bulk Ag. This can prove difficult due to the Volmer-Weber island growth process noble metals exhibit on dielectric materials. Island formation occurs at the initial growth stages, followed by nucleation and coalescence with increasing material deposition. Below the coalescence threshold the optical dispersion does not follow that of bulk Ag and that has a detrimental effect on the optical performance of the coating. In order to lower the thickness at which coalescence occurs we’ve explored highly energetic deposition techniques such as high power impulse magnetron sputtering (HiPIMS) alone or in conjunction with deposition on adhesion layers of Ti, Ge or transition metal nitrides. The adhesion layers also act as barriers to oxidation of the Ag from dielectric materials incorporated in the interference coatings. Using in-situ spectroscopic ellipsometry the coalescence threshold of the Ag was easily monitored by noting when during the growth process the optical dispersion of the film matched that of bulk Ag. A systematic study of the how the adhesion layers and deposition parameters affected the optical properties of the Ag films was achieved by correlating structural and compositional data gather from XPS and X-ray diffraction (XRD) to the optical transmission and optical dispersion obtained by UV-Vis spectroscopy and spectroscopic ellipsometry, respectively.